Engine Performance Final
Technician A says blending 10 percent ethanol into gasoline results in an increase of 2.5 to 3 octane points. Technician B says ethanol is highly corrosive and highly toxic. Who is correct?
A only
Excessive alcohol in the fuel may cause ______.
All the answers are correct.
Which of the following gases is NOT considered to be harmful?
c. O2
Which of the following statements concerning superchargers is NOT correct?
a. Superchargers must overcome inertia and spin up to speed as the flow of exhaust gas increases
Gasoline volatility is being discussed. Technician A says gasoline blended for summer use is more volatile than winter gasoline. Technician B says in high altitude areas, fuels must be blended to have higher volatility.
b. B only
Which of the following is NOT an advantage of an electronic spark control system?
b. It allows lower compression ratio engines to be as efficient as higher compression ratio engines
The longest injector pulse width occurs during ______.
d. cold starting
An injector balance test requires an injector pulse tester and a ______..
d. fuel pressure gauge
Engine vacuum is being discussed. Technician A says that when the engine is operating under light loads, engine vacuum is low. Technician B says that engine vacuum is high when the engine is operated under heavy loads. Who is correct?
d. neither A nor B
What is an advantage of EI ignition?
d. All the answers are correct.
Crude oil is separated into its basic chemical compounds through the process of_____ during which the crude oil is heated to about 1,200°F and vaporized. The different chemical compounds condense at different temperatures as the vapor passes through a cooling tower.
fractional distillation
Which of the following CANNOT be used as a source for the production of hydrogen?
c. Carbon dioxide
Technician A says a loose oil filler cap or a dip stick that is not fully seated in the dipstick tube can change the LTFT on a MAF system. Technician B says the PCV system will draw unfiltered air through these leaks which could result in premature wear of engine parts. Who is correct?
c. both A and B
What tool is needed to test vacuum-type EGR valves?
c. hand vacuum pump
While discussing diagnosis of the control system of a BEV: Technician A begins by checking the voltage of the auxiliary battery. Technician B inspects all fuses, fusible links, wiring harness, connectors, and ground in the low-voltage circuit. Who is correct?
c. both A and B
IAC (idle air control) valves are operated by a ______.
c. stepper motor
The ideal air/fuel or stoichiometric ratio for a gasoline engine is approximately _____ pounds of air mixed with 1 pound of gasoline.
c. 14.7
To read flash codes on an OBD I Chrysler-built vehicle, you must ______.
d. turn the ignition key on and off three times in five seconds, ending with on
Which of the following statements about P-series fuel is NOT true?
Unlike ethanol and methanol, it cannot be mixed with gasoline
The customer complains of a loss of power at highway speeds and a rough running engine at all speeds. A five-gas analyzer reveals these measurements at 2,500 rpm: HC = 700 ppm, CO = 0.2%, CO2 = 9.2%, O2 = 6.2%, and NOX = 330 ppm. What is the most likely cause?
c. lean misfire
A CPI (central multiport injection) fuel injection system for a six-cylinder engine has ______.
d. All the answers are correct.
A plugged fuel filter will cause ______.
d. All the answers are correct.
A restricted catalytic converter may cause ______.
d. All the answers are correct.
An O-ring at the base of a fuel injector ______.
d. All the answers are correct.
A typical four-gas exhaust analyzer does not measure ____ emissions.
d. NOX
Only _____ meets the requirements of OBD II regulations.
d. SFI (sequential fuel injection)
Which statement concerning variable nozzle turbine turbochargers is false?
d. They increase the effects of turbo lag
Before the EVAP system on an OBD-II vehicle can be pressure tested or smoke tested for leaks, a scan tool must be used to _____.
d. close the canister vent solenoid
Which of the following would NOT cause the fuel trim to be out of range?
d. faulty IAC motor (idle air control)
The dwell period on a modern electronic ignition system ______.
increases as engine RPM increases
Technician A says proper tuning of the exhaust manifold tubes can create a partial vacuum that helps draw exhaust gases out of the cylinder, improving volumetric efficiency. Technician B says combined headers allow the cylinders next to each other in the firing order to be combined. This increases exhaust efficiency. Who is correct?
a. A only
Technician A says that gasoline can be used as a source of hydrogen for a fuel cell. Technician B says that carbon dioxide can be used as a source of hydrogen for a fuel cell. Who is correct?
a. A only
Technician A says the EVAP monitor for an OBD-II system determines whether there is sufficient purge flow by varying the purge solenoid duty cycle while monitoring change in STFT. Technician B says the canister vent solenoid must be open during the EVAP pressure test portion of the monitor. Who is correct?
a. A only
Technician A says the main advantage of a turbocharger is that it allows for an increase of power without a substantial decrease in fuel economy. Technician B says the use of exhaust gas to drive the turbocharger robs power from the engine when the vehicle is driven at low speeds. Who is correct?
a. A only
Carbon monoxide is being discussed. Technician A says as the air/fuel ratio becomes richer, the CO levels decrease. Technician B says CO is a colorless, odorless, and highly poisonous gas that can cause death. Who is correct?
b. B only
A/F ratio sensors are being discussed.Technician A says the output voltage of these sensors is much higher than a conventional O2S (oxygen sensor). Technician B say when the output of an A/F ratio sensor is looked at with an OBD-II generic scan tool, the voltage range will appear the same as a conventional O2S sensor, 0 to 1 volt. Who is correct?
c. both A and B
Which of the following should be checked before proceeding with specific fuel injection and electronic control testing?
d. All the answers are correct.
Technician A says CO emissions increase as the air/fuel ratio becomes richer. Technician B says CO emissions increase as the air/fuel ratio becomes leaner. Who is correct?
a. A only
The engine coolant temperature sensor helps to control all the following EXCEPT:
a. fuel pressure
Which of the following is NOT an actuator?
a. PCV valve
A throttle position sensor has ______.
a. a 5-volt reference input terminal
What sensor is used to detect engine misfire?
a. crankshaft position
Technician A says Ford hybrid SUV's with 4WD have an additional motor in the rear axle. Technician B says Ford's Energi models are plug-in hybrids. Who is correct?
b. B only
Technician A uses a low-impedance test light to check for an injector pulse. Technician B uses a noid light to check the injector pulse. Who is correct?
b. B only
When emptying a fuel tank, Technician A drains the fuel into plastic antifreeze containers then caps them tightly to prevent leaks. Technician B drains the fuel into approved gasoline storage containers. Who is correct?
b. B only
While discussing EGR systems with a differential pressure feedback EGR (DPFE) sensor, Technician A says the DPFE sensor sends a signal to the PCM in relation to intake manifold pressure. Technician B says the PCM can make corrections to the EGR flow if the actual flow does not match the desired flow. Who is correct?
b. B only
A sudden increase in TP voltage tells the PCM to _____ to prevent hesitation and stumbling during acceleration.
c. momentarily enrich the mixture
An APP (accelerator pedal position) sensor is found on vehicles with ______.
c. throttle by wire
OBD II technology is being discussed. Technician A says the OBD II system has the ability to store a freeze frame (snapshot) of the operating conditions that existed when the fault occurred. Technician B says vehicle identification must be transmitted automatically to the scan tool. Who is correct?
c. Both A and B
What class of fire extinguisher should be used on gasoline fires?
b. class B
The compressed hydrogen used in FCEVs (fuel cell electric vehicle) is stored at approximately ______ psi.
c. 5,000
Technician A says the action of the wastegate is controlled directly by manifold pressure. Technician B says the wastegate is controlled by the PCM. Who is correct?
c. both A and B
Technician A says a mild hybrid has stop-start, regenerative braking, and electric motor assist available when the engine needs added power to overcome the load. Technician B says a full hybrid has stop-start, regenerative braking, electric motor assist, and can be driven by only electricity. Who is correct?
a. A only
Technician A says an I/M 240 test is four minutes long. Technician B says the test cycle includes acceleration, deceleration, and cruising on an actual road test. Who is correct?
a. A only
Technician A says engine vacuum is normally measured in inches of mercury (in. Hg). Technician B says a pressure gauge that is labeled psig will read 14.7 psi at sea level. Who is correct?
a. A only
Technician A says hybrids have an electrohydraulic brake assist system. Technician B says hybrids have an engine vacuum assisted power brake system. Who is correct?
a. A only
Which of the following is NOT related to photochemical smog?
a. CO
Technician A says if a lean condition caused by a vacuum leak, restricted injectors, dirty MAF, clogged fuel filter, or bad fuel pump exists, the LTFT will have a negative number. Technician B says when the O2 sensor has a rich signal, the STFT goes lean to adjust the air/fuel ratio. Who is correct?
b. B only
Technician A says the oxygen sensor (O2S) detects misfires by monitoring the amount of unburned fuel in the exhaust system. Technician B says a heating element inside the sensor allows the sensor to reach operating temperature quickly and to maintain its temperature during periods of idling or low engine load. Who is correct?
b. B only
Which sensor synchronizes the firing of the injectors and determines when piston number 1 is on the compression stroke?
b. CMP (camshaft position sensor)
How can you identify a flex-fuel vehicle?
b. It has a clover leaf symbol on the exterior or interior.
Which of the following is NOT representative of sequential fuel injection systems?
c. All injectors receive the same PCM commands simultaneously
Fuel injector firing is being discussed. Technician A says SFI systems control each injector separately so that it fires just before the intake valve opens. Technician B says sequential injector firing is more accurate than multiport systems. Who is correct?
c. both A and B
While discussing an ignition problem displayed on a scope primary ignition pattern, Technician A says a worn distributor drive gear can cause an erratic transistor ON signal. Technician B says if there are erratic voltage spikes at the transistor ON signal, the ignition module may be faulty. Who is correct?
c. both A and B
Which statement concerning E85 automotive fuel is false?
d. E85 is more fuel efficient than gasoline.
Technician A says there is maximum EGR flow only when the vehicle is at a cruising speed with a very light load. Technician B says instead of an EGR valve many late-model engines use variable valve timing (VVT) to trap some exhaust gases in the combustion chamber. Who is correct?
c. both A and B
Excessively high CO emissions may be caused by a ______.
c. higher than normal fuel pressure
The fuel pressure regulator can be located _____.
d. All the answers are correct.
Which of the following conditions may result from too little EGR flow?
d. All the answers are correct.
Which of the following is a cause of detonation?
d. All the answers are correct.
Which of the following components is part of both the primary and secondary ignition circuits?
ignition coil
Modern ignition cables contain carbon fiber cores that act as a(n) ____ in the secondary circuit to cut down on radio and television interference and reduce spark plug wear.
resistor
Which of the statements about hydrogen is false?
d. Hydrogen is produced in a fuel cell by breaking down water .
Which of the following is NOT a characteristic of a turbocharger?
d. It requires a mechanical connection between the engine and the pressurizing pump.
A no start/no fuel pressure condition is being diagnosed. When a test light is connected to the pump positive terminal, there is no voltage when the engine is cranked by the starter. What could cause this problem?
d. defective fuel pump relay
Technician A says piezo material is a type of crystal that rapidly shrinks when it is exposed to electrical current. Technician B says piezo material shrinks very slowly when current to it is stopped. Who is correct?
d. neither A nor B
Technician A says that all FCEVs have regenerative braking. Technician B says that all FCEVs have an auxiliary 12-volt battery. Who is correct?
d. neither A nor B
The function of the catalytic converter on a diesel engine is to eliminate ______.
d. particulates (black smoke)
Blowby gases condense in the crankcase and react with the oil to form ______.
d. sludge
Technician A says a lean mixture burns faster than a rich mixture. Technician B says advanced ignition timing induces knock. Who is correct?
b. B only
Crankshaft sensors are being discussed. Technician A says the signal from a Hall-effect CKP cannot be used to synchronize fuel injector timing with the engine. Technician B says some early distributor ignition systems relied on photoelectric sensors to monitor crankshaft position. Who is correct?
B only
Technician A says a plug with a V-notch ground electrode will have two electric arcs jumping across the spark plug gap each time the spark plug fires. Technician B says a spark plug gap that is too wide requires higher voltage to jump the gap, which can cause a misfire. Who is correct?
B only
Vacuum leaks in speed density systems can be verified by watching the _____ on a scan tool.
a. O2 sensor cycle
A digital EGR valve has up to _____ solenoids.
a. three
Technician A says the emission vacuum schematic for the vehicle can only be found in the factory service manual. Technician B says an emissions vacuum schematic is given on a decal under the hood. Who is correct?
b. B only
Which of the following is NOT a metal used for producing exhaust manifolds?
b. aluminum
Which of the following is NOT a component of the Toyota hybrid transaxle?
b. multiple disc clutch
The normal operating temperature for most catalytic converters is about ______.
b. 900°F (500°C)
Technician A says HC emissions are caused by incomplete combustion. Technician B says an excessively lean air/fuel mixture may result in cylinder misfiring and high HC emissions. Who is correct?
c. both A and B
Technician A says a catalytic converter may be tested with a pyrometer. Technician B says a converter may tested using an exhaust gas analyzer. Who is correct?
c. both A and B
Technician A says a defective PCV valve may cause rough idle operation. Technician B says the PCV system depends upon a properly sealed engine to perform correctly. Who is correct?
c. both A and B
Technician A says a pressure gauge can be inserted into the oxygen sensor bore, and back pressure caused by the catalytic converter can be measured. Technician B says a vacuum gauge can be used to identify a restricted converter. Who is correct?
c. both A and B
Technician A says an insulation resistance tester measures voltage. Technician B says an insulation resistance tester measures the effectiveness of a wire's insulation. Who is correct?
c. both A and B
Technician A says diesel engines can be used in a hybrid powertrain. Technician B says a gasoline engine is normally used in hybrid powertrain. Who is correct?
c. both A and B
Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NOX.Who is correct?
c. both A and B
Technician A says the production of CO2 is directly related to the amount of fuel consumed; therefore, more fuel-efficient engines produce less CO2. Technician B says imposing new CAFE (fuel economy) standards will, in effect, reduce CO2 emissions. Who is correct?
c. both A and B
Technician A says turbocharging uses the heat energy in the engine's exhaust gases to drive a pump that compresses the intake air. Technician B says supercharging relies on the rotation of the engine to compress the air.
c. both A and B
The exhaust gas recirculation system reduces ______.
c. oxides of nitrogen
Typical fuel injector pulse widths range from _____ to _____ milliseconds.
a. 1; 10
Fuel lines are being discussed. Technician A says when installing flexible tubing, always use new clamps. Technician B says ordinary rubber hose may be used to replace a kinked steel fuel line. Who is correct?
a. A only
Fuel trim is being discussed. Technician A says a positive fuel-trim value means the PCM detects a lean mixture and is increasing the pulse width to add more fuel to the mixture. Technician B says LTFT [long-term fuel trim] is erased when the ignition is turned off. Who is correct?
a. A only
Technician A says piezoelectric injectors rely on stacked crystals that expand when a voltage is applied. Technician B says piezoelectric injectors are slower acting than solenoid-type injectors. Who is correct?
a. A only
While discussing the reasons why the use of E 85 gasoline is good for consumers: Technician A says it is produced in the United States and can reduce our reliance on foreign oil. Technician B says an engine's fuel consumption is greatly reduced. Who is correct?
a. A only
An accelerator pedal position sensor (APP) is used on vehicles equipped with ______.
a. electronic throttle control
Which of the following sensors is NOT used by the computerized ignition system to control ignition timing?
a. oxygen sensor
Technician A says that dedicated vehicles are those designed to use one particular type of fuel. Technician B says that bi-fuel vehicles can operate solely on an alcohol-based fuel or unleaded gasoline, or a mixture of the two, which gives the driver flexibility and convenience when refilling the fuel tank Who is correct?
b. B only
Technician A says throttle body cleaner may be used to clean the IAC motor internal components. Technician B says on some vehicles, IAC motor damage can occur if the pintle is cleaned with throttle body cleaner. Who is correct?
b. B only
Catalytic converter monitors are being discussed. Technician A says that if the converter is working, the downstream signal frequency should mirror the upstream sensor. Technician B says that the downstream sensor should provide a low-frequency voltage signal. Who is correct?
b. B only
While discussing EI service, Technician A says the crankshaft sensor may be rotated to adjust the basic ignition timing. Technician B says the crankshaft sensor may be moved to adjust the clearance between the pickup coil and reluctor on some EI systems. Who is correct?
b. B only
Which of the following tools cannot be used to test an oxygen sensor?
b. analog voltmeter
The first decision the computer makes in determining the best operating strategy is to determine the _____.
b. engine operating mode
In EI systems using one ignition coil for every two cylinders, Technician A says two plugs fire at the same time, with one wasting the spark on the exhaust stroke. Technician B says one plug fires in the normal direction and the other in reversed polarity. Who is correct?
both A and B
Octane ratings are being discussed. Technician A says most modern engines are designed to use regular grade gasoline. Technician B says to use high octane gasoline only when an engine was designed to use it. Who is correct?
both A and B
Technician A says a loose ignition module mount can cause intermittent misfires or no-start conditions. Technician B says when installing a new ignition module, a small amount of heat conductive grease should be applied to the mounting surfaces. Who is correct?
both A and B
Fuel pressure readings are being discussed. Technician A says high fuel pressure can be caused by a defective pressure regulator. Technician B says low fuel pressure can be caused by a defective pressure regulator. Who is correct?
c. both A and B
Technician A says a defective injector may cause cylinder misfiring at idle speed. Technician B says restricted injector tips may result in acceleration stumbles. Who is correct?
c. both A and B
Technician A says a throttle body may house one fuel injector. Technician B says a throttle body may house two fuel injectors. Who is correct?
c. both A and B
Technician A says diesel engines consume less fuel per mile than a gasoline engine of the same size. Technician B says diesel engines provide more torque than a gasoline engine of the same size. Who is correct?
c. both A and B
Technician A says the IAC counts should change when the A/C compressor is turned on and off. Technician B says if the scan tester indicates zero IAC counts, there may be an open circuit between the PCM and the IAC motor. Who is correct?
c. both A and B
Technician A says the best method for permanently solving a leaking metal fuel tank is to replace the tank. Technician B says a leaking plastic fuel tank can sometimes be repaired. Who is correct?
c. both A and B
Technician A says the biggest disadvantage of using CNG as a fuel is that the large amount space occupied by fuel cylinders limits the driving range of the vehicle. Technician B says bi-fuel vehicles are equipped to store both CNG and gasoline and will run on either.Who is correct?
c. both A and B
If the throttle is held wide open while the engine is cranked over by the starter motor, the fuel management system will enter _____ mode.
c. clear flood
EGR monitors are being discussed. Technician A says some EGR system monitors EGR flow by measuring the difference in pressure as the EGR gas flows through an orifice (restriction). Technician B says some EGR monitors measure the temperature of the EGR outlet to determine whether there is gas flowing through the EGR valve. Who is correct?
c. both A and B
Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor and output status data at the instant the DTC was set. Who is correct?
c. both A and B
Ignition coils are being discussed. Technician A says the primary coil is normally composed of 100 to 200 turns of 20-gauge wire. Technician B says the secondary coil consists of 15,000 to 25,000, or more, turns of very fine copper wire. Who is correct?
c. both A and B
Oxygen sensor monitors are being discussed. Technician A says the system monitors the sensor response time as the system cycles lean-rich-lean. Technician B says that at certain times the monitor varies the fuel delivery and checks for heated oxygen sensor response. Who is correct?
c. both A and B
Resistor-type spark plugs are being discussed. Technician A says the resistor increases the plug firing voltage. Technician B says the resistor helps reduce radio frequency interference (RFI), which can interfere with, or damage, radios, computers, and other electronic accessories, such as GPS systems. Who is correct?
c. both A and B
Technician A says there is less heat energy in high-octane gasoline and, therefore, less power is generated during combustion. Technician B says using a higher-octane gasoline than required will not produce more power unless the engine has a knock sensor that allows the system to adjust ignition timing to take advantage of the higher octane. Who is correct?
c. both A and B
Technician A tests an MAF sensor with a scan tool by watching for erratic changes in flow while the engine idles. Technician B checks an MAF sensor by tapping it lightly with the handle of a screwdriver while watching the waveform on a lab scope. Who is correct?
c. both A and B
Technician A says large, low-speed industrial diesels require a high-quality and highly volatile fuel because they cannot tolerate excessive carbon deposits that result from low-volatile fuels. Technician B says the small, high-speed diesel engines found in passenger cars are relatively unaffected by carbon deposits and can run on low-quality fuel. Who is correct?
d. neither A nor B
A fuel injection system that uses a MAP sensor [manifold absolute pressure] to determine the amount of air entering the engine is called a _____-type injection system.
d. speed density
Air/fuel ratios are being discussed. Technician A says that when the air fuel ratio is higher than 14.7 to 1 the engine produces more power. Technician B says that when the air fuel ratio is lower than 14.7 to 1 the engine uses less fuel. Who is correct?
d. neither A nor B
Leaner air/fuel mixtures ______.
increase the electrical resistance inside the cylinder and increase the required firing voltage
Which of the following is a component of the secondary ignition circuit?
spark plug
Which of the following is not a common cause of preignition?
faulty ignition coil
Where is the fuel pressure regulator on a returnless fuel system?
a. inside the fuel tank
Which of the following would not cause the fuel pressure to drop to zero immediately after engine shut down?
a. leaking pressure regulator vacuum line
Ignition spark typically occurs a few degrees _______.
a. before top dead center (BTDC)
Residual fuel pressure is being discussed. Technician A says remove the fuel filter hose and apply compressed air to the fuel line to push the residual fuel back into the fuel tank. Technician B says to relieve the residual pressure by connecting a fuel gauge with a bleed valve to the Shrader valve. Who is correct?
b. B only
Technician A says a pressure relief valve closes if the fuel supply line is restricted and pump pressure becomes very high. Technician B says the check valve in the pump prevents fuel from draining out of the fuel system and back into the fuel tank. This helps holds residual pressure in the fuel lines after the pump is turned off. Who is correct?
b. B only
A loss of residual fuel pressure immediately after engine shutdown could cause ______.
b. hard starting
Each fuel injector has a _____-wire connector.
b. two
A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can produce a usable signal.
b. 750
Which of the following does NOT use a magnetic pulse generator [PM generator]?
b. throttle position sensor
Fuel line fittings are being discussed. Technician A says that O-rings are used on some fuel line fittings. Technician B says that clamps are used on some systems. Who is correct?
c. both A and B
Which of the following problems would NOT cause a oxygen sensor to appear bad?
d. leaking muffler to tailpipe gasket
What chemical is added seasonally to gasoline as an anti-icing agent to prevent fuel line freeze-up in cold weather?
isopropyl alcohol
Methanol is not commonly used as an automotive fuel because it is ______.
it is highly corrosive
Technician A says spark plugs are part of the primary ignition circuit. Technician B says the battery is part of the secondary ignition circuit. Who is correct?
neither A and B
Reach, heat range, and air gap are all characteristics that affect the performance of which ignition system component?
spark plugs
